on warlock raid compendium i saw this:
Affliction 53/0/18 - Int=0.35 Spi=1.04 SP=1.60 Hit=2.16 Crit=0.90 Haste=1.07
Destruction 0/13/58 - Int=0.31 Spi=1.02 SP=1.59 Hit=3.57 Crit=0.82 Haste=1.10
Demonology 0/56/15 - Int=0.41 Spi=0.93 SP=1.25 Hit=2.63 Crit=0.81 Haste=1.21
this means how much each point of spell power, hit (untill capped), spirit ...etc gives of DPS. according to your spec.
i was watching this and it doesnt seems like logical to me becaue haste should give more dps to aflic than to destru. and crit should give more dps to destru than to aflic.